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Biomedical subjects

Shan-Chwen Chang

Publications and source records attributed to Shan-Chwen Chang.

At least 19 recordsLinked to original sources
PubMed2007

Aberrant induction of regulatory activity of CD4+CD25+ T cells by dendritic cells in HIV-infected persons with amebic liver abscess.

To know why HIV-1-infected persons are particularly susceptible to amebic liver abscess (ALA), we investigated the role of CD4CD25 T cells in the susceptibility of HIV-1-infected persons to this disease. Herein we show, in early stage HIV-1-infected subjects, that CD4 T-cell responses to Entamoeba histolytica antigen (EhAg) were selectively impaired, especially in those with ALA. EhAg-specific CD4 T-cell responses were normalized by depletion of CD4CD25 cells or by addition of anti-cytotoxic T lymphocyte antigen 4 (CTLA4) antibody. Regulatory activity of CD4CD25 T cells to suppress the EhAg-specific CD4 T-cell response could be induced by EhAg-primed dendritic cells (DCs) in HIV-1-infected subjects, especially in those with ALA, but not in healthy controls. Exogenous Tat-incubated DCs derived from HIV-negative subjects also could upregulate CTLA4 expression on autologous CD4CD25 T cells and selectively suppress the EhAg-specific CD4 T-cell response. The results imply an interaction of the two pathogens: HIV-1, perhaps through the effect of Tat on DCs, may upregulate EhAg-specific regulatory T-cell activity to suppress T-cell response to E. histolytica, thus increasing the susceptibility to invasive amebiasis in even early-stage HIV-1-infected persons.

Adult↗
PubMed2006

Brain abscess associated with multidrug-resistant Capnocytophaga ochracea infection.

Brain abscesses are occasionally associated with a dental source of infection. An unusual case of frontal lobe abscess in a nonimmunocompromised child infected with multidrug-resistant Capnocytophaga ochracea is described and confirms the pathogenic potential of this organism to cause human disease in the central nervous system.

Anti-Bacterial Agents↗
PubMed2006

Insufficient perforin expression in CD8+ T cells in response to hemagglutinin from avian influenza (H5N1) virus.

Hypercytokinemia has been considered to be responsible for hemophagocytosis and multiorgan failure in severe human cases of H5N1 viral infection. In this study, we show a recombinant hemagglutinin (H5) from a H5N1 virus may suppress the perforin expression and reduce cytotoxicity of human CD8+ T cells to kill H5-bearing cells. The persistence of H5-presenting cells provides sustained stimulation and leads to a marked lymphoproliferation and IFN-gamma hyperproduction. We propose the IFN-gamma hyperproduction may explain macrophage overactivation and subsequent hypercytokinemia and hemophagocytosis in severe human cases of avian influenza.

Adult↗
PubMed2006

Community-onset Escherichia coli and Klebsiella pneumoniae bacteremia: influence of health care exposure on antimicrobial susceptibility.

Three hundred forty-one case patients with Escherichia coli bacteremia and 173 case patients with Klebsiella pneumoniae bacteremia were enrolled in this prospective observational study to compare the clinical manifestations of infections in the 2 organisms and to delineate the change in resistance of isolates after health care exposure. Liver abscess, primary bacteremia, and respiratory tract infection were more commonly seen in patients with K. pneumoniae bacteremia, whereas urinary tract infection was more common in those with E. coli bacteremia. The influence of prior hospitalization on resistance of E. coli to some antibiotics could be observed for as long as 6 months after discharge. Patients undergoing procedures in the outpatient setting and nursing home residents also had infections with more resistant E. coli strains than those without hospital exposure within the previous year. However, no difference in resistance was observed in K. pneumoniae isolates from patients in different clinical settings.

Adult↗
PubMed2006

Early empirical glycopeptide therapy for patients with methicillin-resistant Staphylococcus aureus bacteraemia: impact on the outcome.

OBJECTIVES: To evaluate whether appropriate early empirical glycopeptide therapy improves outcomes of patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia. METHODS: We retrospectively collected the data for all adult patients with confirmed MRSA bacteraemia diagnosed and treated at National Taiwan University Hospital during the period 1 April 1997-31 March 2001, and followed their survival up to three years. The main outcome measures were MRSA-related death and all-cause mortality. RESULTS: There were 77 MRSA-related deaths among 162 patients. There was no statistically significant difference in MRSA-related deaths between patients receiving glycopeptides before or within 48 h after blood culture (n = 43) (55%, 18/33, non-septic shock group; 90%, 9/10, septic shock group) or those whose glycopeptide therapy was begun more than 48 h after blood culture (n = 119) (37%, 40/107, non-septic shock group; 83%, 10/12, septic shock group) (P = 0.11 and 1.00, respectively). The outcome measure of all-cause mortality from 30 days to 3 years yields similar results. Multivariate logistic regression analysis and Cox analysis showed that the length of delay (daily increment) between blood culture sampling and start of glycopeptide therapy did not have a statistically significant impact on MRSA-related death or all-cause 30-day mortality after adjusting for the effect of other variables [adjusted odds ratio 0.99, 95% confidence interval (95% CI) 0.88-1.12; adjusted hazard ratio 0.87, 95% CI 0.74-1.02, respectively). CONCLUSIONS: The hypothesis that earlier empirical use of glycopeptide therapy reduces mortality in patients with hospital-acquired MRSA bacteraemia was not supported.

Adolescent↗
PubMed2006

Genetic determinants of capsular serotype K1 of Klebsiella pneumoniae causing primary pyogenic liver abscess.

BACKGROUND: Primary pyogenic liver abscess (PLA) caused by Klebsiella pneumoniae is an emerging infectious disease. Capsular serotype K1 and the magA gene have been reported to be associated with this disease. METHODS: The prevalence of magA was determined by polymerase chain reaction (PCR). The sequences of the magA flanking region were completed by inverse PCR and direct sequencing. Serotyping was performed by double immunodiffusion. Insertion mutations and trans-complementation were used to define the K1 genetic determination region. RESULTS: Thirty-five of 42 strains from patients with PLA were magA positive, whereas only 1 of 32 non-PLA strains was magA positive. All 36 magA-positive strains were serotype K1, and the 38 magA-negative strains were not (36/36 vs. 0/38; P<.0001). Sequencing of the magA flanking region revealed a putative capsular polysaccharide synthesis (cps) region; this region was 25 kb in length and contained 20 open reading frames (ORFs); of these ORFs, 9 were cotranscribed as part of an operon and differed from both MGH78578 and the Chedid strain. Mutation of 4 genes in this region turned the mutant strains anti-K1 negative. Trans-complementation restored the K1 phenotype. CONCLUSIONS: The operon containing magA is responsible for capsular serotype K1 of K. pneumoniae. Several loci in the operon are unique determinants of K1 strains.

Antigens, Bacterial↗
PubMed2006

Clinical features and outcome of sporadic serogroup W135 disease Taiwan.

BACKGROUND: Few published reports have evaluated the clinical features and outcome of serogroup W135 meningococcal disease. In Taiwan, W135 is the second most prevalent meningococcal disease serogroup. METHOD: A nationwide study was conducted to retrospectively analyze epidemiologic data from 115 patients with laboratory confirmed meningococcal disease that occurred from 2001 through 2003. RESULTS: Serogroup W135 accounted for 26% of all cases and most (76.7%) were older than 20 years. There were no cases of serogroup W135 meningococcal disease associated with Hajj pilgrims, and all cases were sporadic. In 88 patients with complete case records, we compared the presenting symptoms, signs, laboratory data, and outcomes between W135 and non-W135 patients. There were no differences in presenting symptoms except for the higher prevalence of pneumonia found in W135 patients (23.8% vs. 1.5%; OR: 20.6; 95%CI: 2.3-189.0; p = 0.003). The distribution of inflammatory cells in CSF in patients with meningitis was also different between W135 and non-W135 patients. W135 patients had a trend toward more intubations and shock but it did not achieve statistical significance. In multivariate analysis of factors associated with death, three independent factors were found: bacteremia without meningitis, altered mental status, and petechiae or purpura on admission. CONCLUSION: Sporadic serogroup W135 meningococcal disease is an important component of the meningococcal disease burden in Taiwan, but it is not directly associated with Hajj pilgrims. Compared with patients infected by other serogroups of meningococci, patients with serogroup W135 were older and more likely to have extrameningeal involvement such as pneumonia.

Adolescent↗
PubMed2006

Successful treatment of imported cerebral malaria with artesunate-mefloquine combination therapy.

Treatment of cerebral malaria with intravenous quinine is frequently associated with life-threatening cardiotoxicity. We report a case of imported cerebral malaria successfully treated with artesunate-mefloquine combination therapy. The 27-year-old woman presented with fever, sudden onset of binocular blindness and altered consciousness 10 days after a short stay in Indonesia. Hyperparasitemia with Plasmodium falciparum and P. vivax in more than 5% of red blood cells was demonstrated on peripheral blood smear. She was admitted to the intensive care unit due to shock, jaundice and acute renal failure. Because of a shortage of intravenous quinine, intravenous artesunate was given as an alternative. Her condition stabilized on the 3rd day of therapy, with resolution of fever and disappearance of parasitemia. Consolidation therapy with oral mefloquine and primaquine was then given to prevent recrudescence and relapse. The only adverse event associated with artesunate was transient reticulocytopenia, which resolved after discontinuation of therapy. Her vision completely recovered, along with renal and liver function.

Adult↗
PubMed2006

Evaluation of inpatient clinical training in AIDS care.

BACKGROUND: Studies of outpatient clinical training in AIDS care have shown positive effects on residents' knowledge, attitudes and intentions. In this study, residents' knowledge, attitudes and intentions regarding the care of HIV-infected patients were used as outcome measures to evaluate the effectiveness of a 1-month residency training in an AIDS inpatient unit. METHODS: From April 2000 through April 2001, 33 internal medicine residents completed pretest-posttest questionnaires evaluating changes in their knowledge, attitudes and intention to care for HIV-infected patients. Of these 33 residents, 25 participated in a posttest interview, reflecting on their learning experience during the 1-month clinical rotation. RESULTS: At the posttest, residents were significantly more accurate in assessing HIV-associated risk (p < 0.001), and were significantly more knowledgeable about the necessary protective equipment to prevent HIV transmission (p < 0.01). Residents were significantly less concerned about the risk of infection (p < 0.01) and interpersonal concerns (p < 0.05). Residents' reluctance to care for HIV-infected patients was significantly lower (p < 0.05), as was their tendency to avoid invasive procedures or treatment of HIV-infected patients (p < 0.001). Residents designated after their training were more likely to practice universal precautions and less likely to be afraid and to stereotype HIV-infected patients. They also reported gaining insight into HIV diseases and patients' multifaceted needs, and appreciating the importance of teamwork in AIDS care. CONCLUSION: A 1-month AIDS residency training can effectively enhance residents' HIV-related knowledge, attitudes and intention to care for patients infected with HIV.

Adult↗
PubMed2006

Diagnostic challenge of zygomycosis in compromised hosts.

Rhinocerebral zygomycosis was classically associated with diabetes and diabetic ketoacidosis in the past. In recent years, hematological malignancies and immunocompromised states have become increasingly more frequent underlying conditions for patients with pulmonary and disseminated zygomycosis. In this study we identified 37 patients with a histopathologic diagnosis of zygomycosis and 21 patients with a positive culture for zygomycetes seen at the National Taiwan University Hospital, Taipei, during 1986-2003. Of these, 39 cases with probable or proven invasive zygomycosis were included in these studies. The major underlying diseases were immunocompromised states (74%), and diabetes mellitus (26%). The frequency of zygomycosis in immunocompromised hosts increased from 1.86 during 1986-1991 to 4.13 per 100,000 discharges during 1998-2003. Rhinocerebral involvement was the most common site (74%). An antemortem diagnosis by sinus biopsy was made in 93.1%. Immunocompromised patients were more likely to be younger than diabetics, to have an onset during hospitalization, a positive culture and a postmortem diagnosis. They were less likely than patients with diabetes to receive surgery and more likely to die in the hospital (p < 0.05). Of the 29 patients with invasive rhinocerebral zygomycosis, cerebral involvement (adjusted odds ratio [OR]: 31.7, 95% confidence interval [CI]: 2.4-426.8, p = 0.009) and positive cultures (adjusted OR: 23.8, 95% CI: 1.7-338.6, p = 0.019) were associated with in-hospital mortality by multivariate analysis. Hematological disease and steroid use have become the most important predisposing factors for zygomycosis. Aggressive diagnostic approaches, effective antifungal therapy and surgical debridement are essential for a successful outcome.

Aged↗
PubMed2006

The usefulness of the Platelia Candida antigen in a patient with acute lymphocytic leukemia and chronic disseminated candidiasis.

We report a protracted course of disseminated candidiasis due to Candida tropicalis in a 17-year-old man with acute lymphocytic leukemia. Despite adequate antifungal therapy (amphotericin B), C. tropicalis was recovered from biopsy specimens 25 days (skin) and 109 days (kidney) after the first positive blood cultures. While blood cultures became negative for C. tropicalis 11 days after the initiation of treatment, mannanemia persisted and became negative only after 130 days of antifungal therapy. Thus, antigen assays provided indicators of antifungal response. Differential diagnosis was difficult for this patient with the observation of persistent lesions in image studies. With positive results of antigen assays, an invasive procedure might be avoided and preemptive antifungal treatment could be initiated in a timely manner. Anti-mannan antibody remained undetectable up to 164 days after first positive blood culture despite the patient's recovery from neutropenia and recruitment of neutrophils in the tissue (skin).

Adolescent↗
PubMed2006

Molecular epidemiology of HIV type 1 subtypes in Taiwan: outbreak of HIV type 1 CRF07_BC infection in intravenous drug users.

In Taiwan, sexual transmission is responsible for most HIV-1 infections with two dominant subtypes, subtype B and CRF01_AE, distributing among homosexual and heterosexual groups, respectively. Recently, intravenous drug use has become an emerging route of HIV-1 transmission and contributed to a significant increase of HIV-1 infection. To characterize the HIV isolates responsible for the outbreak among intravenous drug users (IDUs), phylogenetic analysis was performed to analyze the protease/RT sequences amplified from HIV-1-infected IDUs at National Taiwan University Hospital and Taipei City STD Control Center. CRF07_BC, which is circulating in northern China, was demonstrated to account for the majority of HIV-1 infection in IDUs in the past 2 years. Although these Taiwanese CRF07_BC sequences shared the same breakpoint positions as those described in the CRF07_BC reference sequences, they formed a unique cluster in the phylogenetic tree, suggesting they originated from a founder virus. This finding was further supported by the relative low genetic diversity and unique sequence features. Our results demonstrated the emergence of CRF07_BC and its association with the HIV-1 outbreak among IDUs between 2004 and 2005 in Taiwan. This finding not only helps us to have a better understanding of the HIV evolution in Asia, but also has important implications for vaccine design in the future.

Disease Outbreaks↗
PubMed2006

Extended-spectrum beta-lactamase genes of Klebsiella pneumoniae strains in Taiwan: recharacterization of shv-27, shv-41, and tem-116.

Klebsiella pneumoniae causing primary liver abscess (PLA) is emerging. This study identified the beta-lactamases genes of K. pneumoniae isolates in Taiwan. The susceptibilities of beta-lactam antibiotics of 30 K. pneumoniae strains associated with primary liver abscess and 30 noninvasive strains were analyzed. The beta-lactamase genes of randomly selected 24 strains from community-acquired infection and 7 extended-spectrum beta-lactamases (ESBL) strains were identified by PCR and DNA sequencing. Protein expression and the ESBL phenotype of beta-lactamase were determined. All 60 strains were ampicillin resistant and cefotaxime susceptible, whereas no strain was ESBL producing. In the 24 selected strains, shv-1a was found in 14, shv-1 in 7; shv-26, shv-27, and shv-41 were detected in one. However, all of these 24 strains had the tem-116 gene. In 7 ESBL-producing K. pneumoniae strains, shv-5a was found in 5, whereas shv-5 and ctx-m-9 group were detected in 1 strain. Two previously reported ESBL genes, shv-27 and tem-116, as well as a suspected ESBL gene, shv-41, were found in non-ESBL-producing strains. Transformation of these genes conferred ampicillin resistance but not the ESBL-producing phenotype in Escherichia coli. Beta-lactamase protein expression of these strains was further confirmed by western blotting. In conclusion, ESBL is rare in community-acquired K. pneumoniae infection and is not associated with PLA in Taiwan. The shv-5a, shv-5, and ctx-m-9 groups are present in ESBL-producing strains in Taiwan, but shv-27, shv-41, and tem-116 are not ESBL genes.

Cloning, Molecular↗
PubMed2006

Higher seroprevalence of Entamoeba histolytica infection is associated with human immunodeficiency virus type 1 infection in Taiwan.

We assessed the seroprevalence of Entamoeba histolytica infection using indirect hemagglutination antibody (IHA) assay among 667 HIV-infected persons (group A), 1,311 asymptomatic HIV-uninfected persons seeking anonymous HIV testing (group B), 616 HIV-uninfected controls with gastrointestinal symptoms (diarrhea and/or liver abscess) seeking medical care (group C), and 2,500 healthy controls undergoing health check-up (group D). An IHA titer >or= 128 was detected in 7.1% of group A, 2.5% of group B, 1.8% of group C, and 0.1% of group D (P < 0.0001). The highest seroprevalence (11.2%) was noted among HIV-infected persons who were men having sex with men (MSM) 30-39 years of age. Compared with persons with gastrointestinal symptoms, the adjusted odds ratio for having high IHA titers among HIV-infected persons was 3.206 (95% confidence interval, 1.433, 7.176; P = 0.005). These findings show that HIV-infected persons, especially MSM 30-39 years of age, are at significantly higher risk of E. histolytica infection.

Adolescent↗
PubMed2006

Survey of amphotericin B susceptibility of Candida clinical isolates determined by Etest.

BACKGROUND AND PURPOSE: The minimal inhibitory concentrations (MICs) of amphotericin B (AmB) determined by the National Committee for Clinical Laboratory Standards (NCCLS; NCCLS document M27-A) broth dilution method are in a relatively narrow ranges and this may lead to underestimation of the AmB-resistant rate in clinical isolates. We evaluated in vitro susceptibility of clinical isolates of Candida spp. to AmB using Etest and determined the distribution of AmB MICs in different species. METHODS: We used the Etest (AB Biodisk, Solna, Sweden) to evaluate the MICs of Candida isolates randomly collected during 2001-2003 in a teaching hospital. RESULTS: Of the 572 isolates evaluated, Candida albicans (50.7%) was the most common species, followed by Candida tropicalis (23.9%), Candida parapsilosis (13.1%), Candida glabrata (9.4%), Candida krusei (1.9%), and Candida guilliermondii (0.9%). The majority of isolates were from blood (85%). The minimal concentrations of AmB required to inhibit 50%/90% of the isolates (MIC(50)/MIC(90)) were 0.19/0.38 microg/mL for C. krusei, 0.125/0.38 microg/mL for C. glabrata, 0.094/0.25 microg/mL for C. tropicalis, 0.032/0.19 microg/mL for C. albicans, 0.016/0.125 microg/mL for C. parapsilosis, and 0.023/0.032 microg/mL for C. guilliermondii. Only 1 blood isolate of C. glabrata was resistant to AmB (MIC > or =1 microg/mL) [0.17%]. 18.2% of isolates were less susceptible to AmB (MIC > or =0.19 microg/mL) with the highest rates for C. krusei (63.6%), followed by C. glabrata (37.0%), C. tropicalis (29.9%), C. albicans (11.0%), C. parapsilosis (5.3%), and C. guilliermondii (0%). More isolates collected from patients with hematologic malignancy were less susceptible to AmB than those collected from those with other diseases (30.5% vs 15.4%, p<0.05). CONCLUSION: This study demonstrated that AmB resistance remains rare at this hospital in Candida clinical isolates despite increasing use of this agent during the past 4 decades.

Amphotericin B↗
PubMed2006

Improved survival of persons with human immunodeficiency virus type 1 infection in the era of highly active antiretroviral therapy in Taiwan.

We assessed the survival of 1,044 HIV-infected persons enrolled in three periods: period 1, 1994 to 1997 (before the introduction of highly active antiretroviral therapy [HAART]); period 2, 1997 to 2000 (early-HAART); and period 3, 2000 to 2004 (late-HAART). As of 30 June 2005, 259 (24.8%) persons had died after a median observation duration of 985 days (range, 2 - 4,025 days). The mortality rate declined from 33.75 per 100 person-years in the pre-HAART era to 6.51 per 100 person-years in the late-HAART era (P < 0.0001). The adjusted hazard ratios for death in persons with a baseline CD4 count of <200 cells/mul in periods 2 and 3 were 0.605 (P = 0.007) and 0.371 (P < 0.0001), respectively, when compared with persons enrolled in period 1; the adjusted hazard ratio for death was 0.611 for persons enrolled in period 3 when compared to period 2 (P = 0.01). Our study suggested that the survival of persons in the late stage of HIV infection in Taiwan continued to improve in the late HAART era.

Adolescent↗
PubMed2006

Changes in the clinical spectrum of opportunistic illnesses in persons with HIV infection in Taiwan in the era of highly active antiretroviral therapy.

We compared changes in the relative frequencies of opportunistic illnesses (OIs) among 1,044 Taiwanese persons with HIV infection who were enrolled in three study periods from June 1994 to June 2004: before the introduction of highly active antiretroviral therapy (HAART); early HAART; and late HAART. Nearly two-thirds of those newly diagnosed with HIV infection had CD4 counts below 200/mm(3). Among a total of 1,182 OIs, candidiasis, Pneumocystis carinii pneumonia, and tuberculosis were the most common in all three study periods within 3 months after enrollment. Within 3 to 12 months after enrollment, the number of OIs declined significantly. Only 81 cases of OIs were diagnosed, the most common of which were cytomegalovirus disease, tuberculosis, candidiasis, and Mycobacterium avium complex infection. Except for the decreasing frequency of Kaposi's sarcoma, there was no significant change in the relative frequency of each individual OI within 3 months and within 3-12 months after enrollment across the three study periods. We concluded that despite the significant decrease in the number of AIDS-related OIs, the relative frequencies of common OIs did not change significantly after the introduction of HAART.

AIDS-Related Opportunistic Infections↗